1. Field of the Invention
The present invention relates to a semiconductor device having a minute structure body and a manufacturing method thereof.
2. Description of the Related Art
MEMS (micro electro mechanical system) technology which is applied for electronic parts such as a filter, sensors or actuators has been developed.
MEMS is formed using a silicon wafer, has a structure layer forming an interspace, and includes an etching process of a sacrifice layer of the silicon wafer so as to form the interspace. The etching process of a sacrifice layer is a process for forming an opening in the lateral direction to form an interspace, not a process for an opening in the vertical direction as conducted in a manufacturing process of a semiconductor integrated circuit.
As just described above, MEMS has a feature that a substrate is processed three-dimensionally and is essentially different from a manufacturing process of a semiconductor integrated circuit in which a circuit pattern is formed two-dimensionally. Thus, the etching process in manufacturing MEMS takes time and yield is poor, since a form to be processed by the etching is complicated.
For example, in order to shorten the time needed for etching a sacrifice layer, a tunnel structure is formed inside the sacrifice layer by providing the sacrifice layer in two-layer form, and thus, an etching solution goes into the sacrifice layer fast through the tunnel structure at the time of etching of the sacrifice layer (for example, Reference 1: Japanese Published Patent Application No. 2000-58866).